Non-pneumatic resilient tire

ABSTRACT

A non-pneumatic resilient tire which derives its capacity to bear a load from laminated elements capable of supporting bending moments. The laminated elements include a stack of resilient sheets superposed and separated by a layer of rubber adhering to the latter, forming a beam capable of undergoing bending stress.

This application is a divisional application of U.S. patent applicationSer. No. 09/466,524, filed Dec. 17, 1999, which issued as U.S. Pat. No.6,640,859 on Nov. 4, 2003, and which claims priority from French patentapplication No. 98/16175, filed Dec. 18, 1998.

BACKGROUND OF THE INVENTION

The present invention concerns vehicle wheels of any type and, inparticular, a non-pneumatic tire designed to be capable of bearing aload without inflation pressure.

It is known that the reinforced rubber tire inflated to working pressurehas come into common use, so great are its qualities of comfort andsturdiness. It has been successfully adapted to applications asdifferent as passenger vehicles, construction equipment, airplanes,motorcycles, farm machinery, heavy trucks, etc. The inflation pressuremakes it possible to bear a load and distribute it on the surface.

Although the reliability of a pneumatic tire has become remarkable, itis known that the risk of a flat is not totally eliminated. The problemis that, in case of loss of inflation pressure, or even more insidiouslyin case of a substantial reduction of inflation pressure, the tire is nolonger able to render the service for which it is designed under goodconditions. Hence, there has been a multitude of proposals fornon-pneumatic tires (see, for example, U.S. Pat. No. 5,050,656), theobject of which is to eliminate the main cause of tire failure (flats),but which have not come into use for lack of being able to offer asufficient level of comfort and/or endurance and/or capacity to bearheavy loads. Hence, there have also been numerous proposals aimed atproviding tires with a greater capacity to roll temporarily withoutinflation pressure, for example, as described in U.S. Pat. No.5,535,800.

The proposal cited above has, however, the disadvantage that it iscomplicated, if not impossible, to design a tire whose sidewalls remainresilient and can tolerate suddenly mounting a curb without damage. Infact, the reinforcing elements incorporated in the sidewalls risk beingbent, in case of very marked stress, to the point that their radiallyouter end joins their radially inner base. In that case, if thoseelements are locally gripped to the extent of resulting in very smallradii of curvature, their breaking point or their elastic limit will beexceeded, depending on the materials used. The object proposed does nottherefore provide sufficient safety, since there is a strong likelihoodthat the tire will be destroyed (or even worse, locally degraded in adangerous but not immediately apparent manner) by certainly extreme butnot abnormal stresses (shock on a sidewalk curb). An ordinary tire, evenwhen greatly deflated, tolerates these stresses much better due to itsvery flexible sidewalls, incapable of bearing the load by themselves.

The state of the art shows, by wavering between radical solutions(non-pneumatic tire wheel) and the solutions providing tires with alimited capacity to roll without pressure, that the problem of possibletire failure is extremely difficult to solve.

Furthermore, even without tackling the problem of failure, a tire ascurrently designed presents other disadvantages to which we have becomeaccustomed for a very long time. It can be observed that a bead is sodesigned that it can be mounted and demounted from the rim, while beingable to transfer the working stresses between the tire and the rimthrough sufficient tightening of the tire on the rim. This requires arather delicate adjustment. It results in the rather solid and rigidconstruction known. But considering service rendered the users, there issome waste of material, for the use of a portion of same can beexplained only for securing the mountability and demountability of thetire.

It is also known that the compromise between comfort (all the greaterthe more flexible the sidewalls) and performance (precise steering,which results in stiffening the sidewalls and/or in developing smallerand smaller sizes for passenger vehicle tires) is very difficult toarrange. It is also known that there is a great propensity for tires ofa passenger vehicle to lie down under the front wheel on the outside ofa turn in case of high transversal acceleration. In this case, the tireworks quite poorly, letting the tread go too much and bearing on theroad with the shoulder of the tire.

SUMMARY OF THE INVENTION

The object of the present invention is to propose a non-pneumatic tirethat can truly be used without inflation pressure, which will becapable, like the pneumatic tire, of bearing a substantial load whileproviding good comfort, good adherence and good capacity to transmitconsiderable lateral thrusts. It is a question of proposing analternative solution to the pneumatic tire. It is not simply a questionof providing a tire with the temporary capacity to run flat.

The invention proposes a resilient non-pneumatic tire having an axis ofrotation and essentially containing a tread carried by a resilientbearing structure radially situated inside the tread and defining, atleast partially, an inner cavity of revolution, the bearing structurecomprising:

a zone of attachment radially on the side of the axis of rotation, forthe locking of the bearing structure on means of connection to a hub,and the zone of attachment being axially placed between the laterallimits of the bearing structure, the attachment zone being designed forcontacting the means of connection to a hub, the means of connection toa hub being designed to form a rigid assembly,

a plurality of support elements, extending essentially crosswise, placedbetween the zone of attachment and the tread, the support elements beingjuxtaposed circumferentially and distributed all around thecircumference, the support elements being fitted in the zone ofattachment, each support element containing a bundle of superposedresilient base pieces, separated by a layer of elastomer adhering toeach of the base pieces, so as to form a beam capable of undergoingbending stress,

an interconnecting structure between the support elements, arranged sothat a portion of a radial stress of a support element is transferred tothe adjacent support elements circumferentially, while allowingdifferences in displacement between adjacent support elements.

The capacity to bear a load, in the proposed non-pneumatic tire, is dueessentially to the support elements. Distributed circumferentially, thesupport elements successively come into play for contribution in takingup the load when the non-pneumatic tire is rolling. Several preferablycome into play at the same time in the footprint. The support elementsare transversely oriented and essentially stressed on bending in orderto make their individual contribution to taking up the load (that is,the so-called “Z” stresses). Other stresses do exist, but it will beapparent that the elements are essentially stressed on bending.

Turning to the embodiments of each support elements, it will be shownthat they comprise a bundle of flexible base pieces each of which isribbon-like. The flexible base pieces are stacked radially, withinsertions of elastomer adhering on each of the flexible base pieces.The beam thereby built is able to sustain bending in a radial plane.This feature of the support elements is however by no means limitative,namely if it is noted that the support elements have to sustain otherdeformations, since they do not all deform in a identical waysimultaneously, as it will become more apparent hereunder. By describingthat the means of connection to a hub form a rigid assembly, it isintended to point out that the whole deflection between the ground andthe axis of rotation comes from the deflection of the non pneumatictire, and not from a rim, a wheel or any suitable device for connectingto a hub, just like a conventional pneumatic tire with respect to itswheel.

DESCRIPTION OF THE DRAWINGS

The invention is explained more in detail by the description of threenonlimitative working examples illustrated in the attached figures, inwhich:

FIG. 1 shows a radial section of a first embodiment of a non-pneumatictire according to the invention, having a tread of convex shape,resembling the tires designed to operate accepting wide angles ofcamber;

FIG. 1A is a radial section, similar to FIG. 1, of a second embodimentof a non-pneumatic tire according to the invention;

FIG. 2 is an enlargement of the part surrounded by circle A in FIG. 1;

FIG. 3 shows the same non-pneumatic tire deformed to an intermediatedeflection level;

FIG. 4 is a section along IV—IV in FIG. 1;

FIG. 5 is a section along V—V in FIG. 1;

FIG. 6 shows a radial section of a second embodiment of a non-pneumatictire according to the invention, having a tread of rather flat shape,common for tires designed to operate at zero or very narrow angles ofcamber;

FIG. 7 shows the non-pneumatic tire of FIG. 6, deformed to anintermediate deflection level;

FIG. 8 shows a radial section of a third embodiment of a non-pneumatictire according to the invention, also having a tread of rather flatshape, common for tires designed to operate at zero or very narrowangles of camber;

FIG. 9 shows the non-pneumatic tire of FIG. 8, mounted on a differentrim;

FIG. 10 is a partial sectional perspective, diagrammatically showingessentially the structure of the non-pneumatic tire according to thethird embodiment without load, in a state free of any stress;

FIG. 11 is a partial sectional perspective, showing essentially thedeformation under load of the structure of the non-pneumatic tireaccording to the second and the third embodiments.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a non-pneumatic tire having a tread 11 with a generallycurved shape. The wall of the tire essentially contains two parts called“first and second structure parts 11I and 11E.” These first and secondparts are radially superposed and form two springs acting in series andare respectively arranged radially inward and radially outward. Onecharacteristic of this first embodiment is the pseudohinge separatingthe first 11I and second 11E structure parts, which constitutes a zoneof lesser bending strength. This zone of the tire, by its constitution,does not oppose or just slightly opposes folding, that is, the relativerotation of the end parts of the first radially inner structure part andsecond radially outer structure part. The ends of each of the first andsecond bearing structure parts are situated roughly at the lateral endsof the bearing structure. The support elements consist of laminatedelements 12. Each support element of the first bearing structure partgoes from one lateral end to the other lateral end. The profile of theradially outer surface resembles that of motorcycle tires.

The laminated elements 12 are capable of supporting bending moments to amuch greater extent than the cords—even wires—ordinarily used toreinforce tires. The laminated elements 12 embody a stack of resilientsheets 13 superposed and separated by a layer of rubber 15 (see FIG. 2).It is suggested here to use rubber as elastomer but it is not limitive.The take-up of a load makes each of the sheets 13 work bending and therubber of each layer 15 work shearing. The thickness of each layer 15(which can, furthermore, vary), the thickness of each sheet 13 (whichcan also vary), the number of sheets, the modulus of elasticity of thematerials used for the sheets, the modulus of elasticity of theelastomer used and the arrangement of the sheets are some of theparameters making it possible to adjust the properties of thenon-pneumatic tire (which means adjusting the curve giving responsibleforce to the capacity of the tire to bear a load depending on deflectionof the tire, commonly described by the expression “load-deflectioncurve”).

The sheets are, for example, constituted essentially by a thermosettingor thermoplastic resin matrix, reinforced by fibers mainly arrangedlongitudinally in each sheet, that is, parallel to a meridian plane(that is, a plane containing the axis of the tire) in the non-pneumatictire. Glass fibers yield good results, but fibers of another kind couldalso be used, depending on the advantage contributed by theircharacteristics. One can imagine numerous working variants of thesheets. For example, as can be seen in FIG. 2, each sheet is formed bythe superposition of bands 14 glued to one another.

The bands can, for example, be glued in place, that is, in thenon-pneumatic tire being manufactured. This is one solution among othersfor making sheets without preload or at least with a negligible preload,when installed in the non-pneumatic tire with the desired curvature, asdrawn in FIG. 1. The advantage of thin bands is that, with any method ofmanufacture for the bands, they can easily be made to follow exactly anyfinal shape, the final shape being that targeted for a sheet. The bandscan be glued together, for example, by means of a fine layer ofelastomer or by means of a resin, rendering the sheets more monolithicin the latter case.

The invention thus extends to a method of manufacture of a resilientnon-pneumatic tire having an axis of rotation and a bearing structurehaving a median plane perpendicular to the axis of rotation and definingan inner cavity of revolution, the bearing structure containing aplurality of support elements distributed all around the circumference,each support element being placed roughly crosswise, each supportelement being a laminated element containing a stack of resilient sheetssuperposed radially, a method in which the constituents required forbuilding the non-pneumatic tire are placed on a destructible support,and the method embracing, notably, the following steps:

bringing a section of the band on the support,

bending the section to make it follow exactly the shape of the support,

locking the ends of the section,

repeating the preceding stages until obtaining the stacking desired.

In this first embodiment, a laminated element 12 is arranged on theradially inner side and on the radially outer side of the non-pneumatictire. Each laminated element 12 includes a bundle of super-imposedsheets, or base pieces, 13. The axial length of each of the sheets 13relative to that of the other sheets decreases the further is that sheetfrom the cavity outward. That is, a sheet 13 has a shorter axial lengthrelative to another sheet 13 which is closer to the cavity of thenon-pneumatic tire. This is what appears in FIGS. 1 and 3. Using thisarrangement, the characteristics of resilience of the non-pneumatic tirecan be adjusted by adapting the stack of sheets 13 in the laminatedelement 12 to the bending moment that it is necessary to support locallyand by adapting the stack to the deflections it is desired to obtain.

Each laminated element, at least in the radially outer bearing structurepart, is preferably symmetrical and axially centered. Finally, let uspoint out that the zone of attachment 110 is preferably in one piece, ascan be seen in FIGS. 1 and 3. This means that this part, intended to beattached to a rim, does not present any laminated structure. Forexample, it contains only a resin matrix and reinforcing fibers, ofcourse, preferably of the same component materials as the sheets, and itcontains no rubber. This connection zone is so designed to undergobending stresses.

After having described the main aspects of the architecture of thenon-pneumatic tire, seen in meridian section, let us examine what is itsarchitecture seen in circumferential section, referring for this purposeto FIGS. 4 and 5. Also preferably, in a laminated element, consideringthat the width “1” is the dimension of the sheets being displaced alonga sheet following a circumferential orientation, the width 1 of thesheets is constant (see FIGS. 4 and 5, as well as FIGS. 10 and 11, forthe reader will have understood that this aspect, like many othersdescribed, is also true for the other embodiments). It can, in fact, besimpler to manufacture only sheets of the same width. Of course, as isevident on comparing FIGS. 4 and 5, since the width 1 of the sheets 13is constant, the space between laminated elements 12 is less in theradially inner bearing structure part 11I than in the radially outerbearing structure part 11E.

Furthermore and still preferably, the width “1 _(s)” of the supportelements (considered circumferentially) is such that the number ofsupport elements in the whole circumference is at least 80. This isroughly drawn in FIGS. 10 and 11. This renders the tire sufficientlyuniform, although the bearing structure thus made cannot be consideredhomogeneous circumferentially, for example, for its modeling. Such abearing structure presents a cyclical symmetry, according to a standardterminology. To further improve uniformity, the number of supportelements can be increased and their width 1 _(s) can be concomitantlydiminished in the circumference. The non-pneumatic tire according to theinvention is then advantageously such that, considering width 1 _(s) thedimension of the support elements on being circumferentially displaced,the width 1 _(s) is such that the number of support elements in thewhole circumference is at least in the order of 200.

In the radially outer bearing structure part, the proposedinterconnecting structure contains circumferential reinforcements atleast under the tread. They are, for example, circumferential wires 16that can be seen, notably, in FIGS. 1 and 4. The wires ensure thestability of the dimensions of the non-pneumatic tire on centrifuging.Furthermore, the circumferential wires 16 help distribute the load of asupport element (laminated element 12) on the adjacent laminated elementor elements 12. If one can imagine, notably, what happens if a supportelement (laminated element 12) mounts an isolated obstacle, the latteris going to tend to be avoided, for the load tends to be applied only onthat laminated element instead of being distributed over severallaminated elements. As soon as the overloaded laminated element bendsmore than the adjacent ones, the circumferential wires 16 pull on theadjacent laminated elements 12, thus transferring a part of the load.This leads to a certain warping of the support elements. The supportelements are designed so that they can sustain a certain degree ofwarping stress. The proposed embodiments, having laminated element 12with base pieces (resilient sheets 13) stacked radially with rubberlayer 15 inserted in between, are able to accommodate the encounteredwarping stress. But of course other embodiments are achievable. Thenon-pneumatic tire is thus capable of absorbing an isolated obstaclelike a stone on the road. Furthermore, the circumferential wires 16contribute to passage of the torque by distributing the stress over allthe laminated elements 12 on the whole circumference of thenon-pneumatic tire.

Furthermore, the proposed interconnecting structure also contains arubber matrix 165 separating the sheets circumferentially (see FIG. 4).The interconnecting structure could contain only rubber ensuring aconnection between support elements, for example, for applications ofthe invention to moderately stressed non-pneumatic tires. In the exampledescribed, the rubber completely fills the space between two adjacentlaminated elements. In addition, a layer of rubber completely covers thestructural reinforcements of the non-pneumatic tire, thus creating acontinuous outer skin like standard tires. Of course, other variants canbe developed, for example, devoid of rubber or with much less rubberradially under the circumferential wires 16. This can prove advantageousfor attaining a lesser level of rolling resistance.

In the present application, the term “wire” is used in a generic sense,meaning that the wire is supposed to present characteristics sufficientto transfer a portion of the radial stress to the adjacent supportelements and to transmit the load beyond the footprint. One can usemonofilaments, multifilaments or assemblages like cords or even anyequivalent structure, regardless of the material or materials of thosewires, their moduli and any treatment of those wires, like surfacetreatment or coating or precoating to favor adhesion on the rubber.“Circumferential” means an orientation at an angle of zero degreemeasured in relation to a plane perpendicular to the axis of rotation ofthe support, thus observing the usual conventions for tires. Inpractice, the reinforcement can be made by coiling of a wire, with acertain pitch, resulting in the angle not strictly being zero, but, inpractice, at least locally greater than zero degree, in order to be ableto sweep the entire width desired.

There is nothing imperative, however, about the arrangements describedin the three foregoing paragraphs. The laminated elements can beinterconnected by layers of a nature similar to layers 13 of each stack.Many other forms of interconnection can be carried out. In short, and tostate the essentials, the laminated elements bear the load; they do notwork completely isolated from one another, but are connected together toensure good overall operation, avoiding overly intense shearing betweentwo adjacent laminated elements and so as to offer good uniformity, thatis, a relative constancy of properties, regardless of thecircumferential position of the non-pneumatic tire relative to thesurface.

Returning to the connection between the radially outer bearing structurepart 11E and the radially inner bearing structure part 11I, which wasthe to form a sort of hinge 17, appreciably inextensible radial wires170, embedded in a rubber matrix, cover the junction of the outer sideof the latter, in order to integrate correctly the radially innerbearing structure part and the radially outer bearing structure part.These radial wires 170 are placed in the zones of lesser bendingstrength and are embedded in a rubber matrix. As a variant shown in FIG.1A, each radial wire is placed relative to the support elements of theinner cavity side on one of the bearing structure parts (see wires 170 aand 170 c) and of the outer side on the other one of the bearingstructure parts (see wires 170 b and 170 d), some of the successivewires on the first radially inner bearing structure part being placedoutside and the others being placed inside the inner cavity, preferablyalternately.

In this first embodiment, the laminated elements 12 resemble compoundsprings, except that here the sheets are fixed to one another by a layerof rubber. The radially inner and outer bearing structure parts 11I and11E present, in the whole meridian plane, a quasisymmetry on both sidesof a virtual cylinder passing through the hinges 17. The radially outerand inner bearing structure parts 11E and 11I are so constructed thateach takes approximately half the deflection resulting from a loading,which is favorable to endurance of the zone forming a hinge, fordeflection is possible with relative motion of the axial ends of thebearing structure parts. FIG. 3 shows the shape of the non-pneumatictire loaded.

It is to be understood that, in case of very considerable overload, due,for example, to a shock against a sidewalk curb, the radially outerbearing structure part naturally abuts the radially inner bearingstructure part. This occurs well before the laminated elements mighthave been bent to the breaking point. This is why the non-pneumatic tireproposed in the invention contributes a very sturdy solution, offeringgood endurance under the effect of the most severe stresses that mightbe encountered in normal service on a vehicle.

The non-pneumatic tire illustrating the first embodiment described abovecontains laminated elements arranged roughly radially. As is known fromoperation of a standard radial tire, it is noted that the laminatedelements accommodate a slightly non-radial orientation. That means thatthe reinforcing elements, which are normally radially oriented in thesidewalls (carcass cords in a conventional pneumatic radial tire,support elements in the described embodiments proposed in thisspecification), leave somewhat their genuine radial orientation, themaximum value of deviation being observed on entry and on exit of thefootprint. Consequently, passage into the footprint, in addition tobending, the support elements are subjected to torsion and stress. Thisdeviation with respect to the radial orientation is possible as thesupport elements are designed to accommodate deformations other thandeflection in a radial plane.

As for attachment on means of connection to a hub, the tire can beattached to a wheel disk or any other member securing rigid functionalconnection with a hub. The tire and wheel assembly presents, in themanner known for pneumatic tires, a transverse rigidity sufficient to beable to guide a vehicle, notably, on turns. As far as the non-pneumatictire is concerned, one or more circumferentially inextensiblereinforcements, for example, rigid hoops 18 for the first embodiment,are placed in the zone of attachment and contribute to good locking ofthe tire on its rim in case of transverse stresses.

FIG. 6 illustrates a second embodiment, in which the non-pneumatic tireprofile, seen in meridian section, resembles the profile of a tiredesigned to work at small or zero camber angles (like passenger tires).The sidewalls are rounded and lie in almost all of the radial height ofthe non-pneumatic tire. The bearing structure essentially containslaminated elements 22 comprising a stack of resilient sheets 23,superposed and separated by layers of rubber 25; and embodies thesupport elements. An attachment zone 210 is arranged substantially inthe middle of the radially inward wall of the non pneumatic tire. Thesupport elements jump over the attachment zone and project beyond theattachment zone, and as in the first embodiment are fitted so as to beable to undergo bending stresses.

The parameters of size and adjustment of properties of the non-pneumaticaccording to this second embodiment are, notably, those previouslymentioned, namely, the thickness of layer 25 and each sheet 23, thenumber of sheets, the modulus of elasticity of the elastomer materialsemployed for the sheets, the modulus of elasticity of the elastomerused, and the arrangement of the sheets. Likewise, for the compositionof the sheets 23, references should be made to the explanations suppliedfor sheet 13. The non-pneumatic tire also contains circumferentialreinforcements (not shown) under the tread.

The non-pneumatic tire contains a tread 21, which can be very slightlybent when it is not supporting any load. The radially outer part of thebearing structure, that is, the zone containing the tread 21 and thepart of the sidewalls 29 close to the tread 21, contribute only verylittle to deflection (radially) under the effect of the load. Thesidewalls 29 and, in particular, the radially inner part of the latter,as well as the radially inner wall of the bearing structure, are theseat of deformations responsible for most of the deflection under load.The part of the radially inner bearing structure, which at zero load isappreciably straight (see FIG. 6), parallel to the axis of rotation,takes a bowed shape, the concavity of which is directed inward (see FIG.7), which is accompanied by a slight relative coming together of itslateral limits. This type of deformation applies to each of the lateralzones of the bearing structure under the tread, a moment tending totransfer the load to the central zone of the tread and concomitantly torelieve the shoulders of the tire, which on the whole makes it possibleto ensure a relative constancy of pressures on the surface in thefootprint.

Just as in the first embodiment, the tire is attached to a wheel disk orto any other member ensuring rigid functional connection with a hub. Theassembly presents, in the median zone of the radially inner wall of thebearing structure, a transverse rigidity sufficient to be able to guidea vehicle, notably, on turns.

Let us further note that the properties of the non-pneumatic tire can beadjusted by working on the design of the means of connection to the hubof the non-pneumatic tire, called “rim” for sake of convenience. By moreor less widening the bearing surface 291, preferably symmetrically, theradial resilience of the non-pneumatic tire can be adjusted, somewhatlike the inflation pressure of a pneumatic tire, which is adjusted for atire of the same model according to the vehicle equipped, according tothe axle of the vehicle and according to whether the vehicle is usedloaded or empty. Therefore, depending on the rim used, the radialresilience of the tire mounted on its rim varies.

The invention extends to a rim intended to be used with a deformablenon-pneumatic tire designed as explained above, the rim containingmounting means for receiving and locking the zone of attachment of thetire and containing, on at least one side axially (and preferably onboth sides), a seat extending roughly parallel to the zone of attachmentof the non-pneumatic tire, in which the axial position of the axiallyoutermost point 284 still in contact with the non-pneumatic tire isadjustable (see FIG. 7, it being known that the bearing surface islocated axially between the axially outermost points 284, or 384 in FIG.9). In this way, the bearing surface 291 of the tire on the rim can bevaried. All along the bearing surface, the wall of the tire cannot beradially displaced toward the axis of rotation, which alters operationof the tire wheel.

FIGS. 8 and 9 illustrate a third embodiment very similar to the second.A tread 31 and support elements 32 are provided. The interconnectingstructure contains circumferential reinforcements 36 in sheet form. Thezone of attachment 350 is circumferentially slotted (not shown in thesimplified views of FIGS. 10 and 11), so that the non-pneumatic tirepresents a slot 315 defined between two connecting ribs 320 which arecapable of being axially displaced relative to each other. Theconnecting ribs 320 are each intended to come in contact with the meansof connection to a hub, notably, through a contact bearing 391 on theradially inner side of each of the connecting ribs 320. The ribs 320 arethe attachment zone 350 referred to hereinabove.

It can be seen in FIG. 8 that the latter resembles a narrow rim designedto grip the connecting ribs 320 by means of a profiled part 321 ofsuitable shape. As shown in FIGS. 8 and 9, the profiled part 321 extendsradially through the slot 315 between the two connecting ribs 320. Awheel disk 38 extended by a first flange 380 can be seen. A secondflange 381 is mounted on the disk 38 by means of screws and nuts 382,with insertion of the profiled part 321 and connecting ribs 320 of thenon-pneumatic tire. The profiled part 321 is a rotating piece whosemeridian section is clearly visible in FIGS. 8 and 9, and which can beslotted and therefore interrupted circumferentially, so as to facilitateits insertion between the ribs 320 of the non-pneumatic tire. Next, thenon-pneumatic tire, with the profiled part inserted between the ribs320, is correctly positioned relative to the first flange 380, and thenthe second flange 381 is fastened on the first, with interposition ofthe profiled part. Part 321 makes it possible, with the first and secondflanges 380 and 381, to grip the connecting ribs 320, so that thenon-pneumatic tire is fitted on the means of connection to the hub,which is the preferred mounting of the non-pneumatic tire.

Thus, the invention also extends to a rim containing mounting means forreceiving and locking a resilient non-pneumatic tire having an axis ofrotation and essentially containing a tread carried by a resilientbearing structure radially situated inside the tread and defining, atleast partially, an inner cavity of revolution, the bearing structureembracing a zone of attachment radially on the side of the axis ofrotation, for the locking of the bearing structure on means ofconnection to a hub, the means of connection to a hub forming a rigidassembly, the zone of attachment being placed axially between thelateral limits of the bearing structure, and the zone of attachmentbeing circumferentially slotted, so that the tire presents twoconnecting ribs 320, capable of being axially displaced in relation toeach other, the rim including:

two flanges 380, 381, each serving as seat for one of the two ribs 320,

a profiled shape 321 designed to cooperate with the flanges 380, 381 inorder to grip the ribs 320 and to lock them on the rim.

The form of manufacture of the non-pneumatic tire can be different fromthe form of use required by the means of connection taking the place ofa rim. For example, the connecting ribs 320 can be forced to cometogether axially on mounting. The widened shape of the connecting ribs320, forming a sort of dovetail, helps avoid any accidental demountingof the tire under the effect of the prestressing installed in same. Theresilience can thus be adjusted by a preload in the laminated elements32 according to the relative axial separation between the connectingribs 320 of the non-pneumatic tire.

Furthermore, just as already explained above, depending on the size ofthe contact bearing 391, it is possible to act on the deflection by thenon-pneumatic tire. Supplementary rings 383 can also be added to widenthe bearing surface of the non-pneumatic tire for the purpose mentionedabove (see bearing 391 b in FIG. 9).

Finally, FIGS. 10 and 11 represent the general shape of the resilientbearing structure. Comparison of those figures shows the deflectionobtained with a non-pneumatic tire according to the invention. A certaindegree of deviation with respect to the radial orientation exists in allthe embodiments. This is notably evident at the bottom of FIG. 11, bycarefully observing the bent zone D, where it can be seen that thedeflection of the support elements come with a certain degree ofwarping, the more the support element is offset of the section plane ofFIG. 11 while bending in the footprint, the greater the deviation is.

In the examples illustrating this specification, the support elementstake the form of laminated elements. The bundle of base pieces istherefore formed by a stack of sheets, with insertions of rubber,whatever the construction of the sheets themselves.

In light of the following description, the function of these supportelements will more readily appear, and the person of skill in the artwill, of course, be able to substitute those laminated elements withother forms of construction, that is, substitute the sheets with otherforms for the base pieces, provided that the support elements offer theradial flexibility sought and make the required contribution to take-upof the load and are also capable of offering suitable characteristics inresponse to the nonradial stresses seated in such non-pneumatic tires(transmission of so-called “X” and “Y” stresses) and of working inharmony with the adjacent support elements. In other words, the bearingstructure, on being deformed, makes possible a certain flattening of thezone under the tread concerned on contact with the surface, so that thetrack of the loaded tire on the surface takes a certain form, as in thewell known operation of inflated tires.

Each support element is present at least in the part of the bearingstructure lying between the lateral ends of the bearing structure andthe tread and not necessarily under the tread, although in the examplesdescribed the support elements are continuous under the tread. Onecould, however, as a variant and at least under a substantial part ofthe tread, replace the stack of sheets, that is, the bundle of basepieces, with a rather rigid ring of the type proposed as reinforcementunder the tread in U.S. Pat. No. 4,111,249. The stack of sheets can alsobe replaced with a relatively rigid stud; a large number of studs arearranged circumferentially, the set of studs being articulated with oneanother and thus forming a sort of circumferential track (see, forexample, the reinforcing structure under the tread described in patentapplication EP 0,836,956). More generally speaking, any structure couldthus be placed under the tread, provided that it is capable oftransferring a shear to the lateral parts of the non-pneumatic tire.

In all the variants proposed, the part of the radially inner bearingstructure closest to the axis of rotation makes an importantcontribution to the deflection under load and, therefore, to the comfortprovided by the tire. Hence, it is advisable for the zone of attachmentto be located preferably on a fraction corresponding to not more than50% of the distance axially separating the lateral limits of thenon-pneumatic tire. The radially inner part of the resilient bearingstructure thus rather markedly projects beyond the zone of attachment. Afavorable structural arrangement is for the support elements to beoriented, just beyond the zone of attachment, in a direction roughlyparallel to the axis of rotation. This is what appears in the examplesdescribed below. Finally, the nonpneumatic tires described beingsymmetrical, the zone of attachment is roughly centered between theaxial limits of the non-pneumatic tire, without this being limitative. Adissymmetrical architecture could, of course, be adopted, notably, inthe location of the zone of attachment.

As for the degree of contribution to the deflection under load of thepart of the radially outer bearing structure, it can vary with theembodiments.

In the first example proposed, the bearing structure contains a firstradially inner bearing structure part and a second radially outerbearing structure part, the first and second bearing structure partsbeing integrated with each other by a zone of lesser bending strength,each of the first and second bearing structure parts containing thesupport elements, and each support element of the first radially innerbearing structure going at least from a lateral end to the zone ofattachment, so that the zones of lesser bending strength between thefirst and second bearing structure parts are, under the effect of theworking stresses, radially mobile in relation to the zone of attachment.Each support element of the second radially outer bearing structurepreferably goes from one lateral end to the other lateral end of thesecond bearing structure part.

The radially inner bearing structure part forms two zones which overhangthe rigid central connection. According to the invention, these twozones fully share in the flexibility of the non-pneumatic tire. This iswhat it was intended to express above on stating that the zones oflesser bending strength are, under the effect of the working stresses,radially mobile in relation to the zone of attachment. This has oneclear consequence, valid moreover for all the embodiments: to permitefficient operation of the non-pneumatic tire according to theinvention, no obstacle should prevent elastic deformation radiallyinward from the radially inner bearing structure part, that is, the partleading to the rigid central connection. The latter, on bending, comessomewhat close to the axis of rotation. The shape of the non-pneumatictire on maximum bending therefore dictates a limiting casing inside ofwhich one cannot encounter any of the mechanical parts of the vehicle:wheel disk and/or rim, braking parts, suspension parts, etc.

In the first of the examples illustrated, the degree of contribution todeflection under load of the radially outer bearing structure part isroughly equivalent to the degree of contribution to deflection underload of the radially inner bearing structure part. Of course, the zoneof lesser bending strength can be less localized and can involve agreater portion of the wall of the bearing structure.

In a second embodiment, the support elements are continuous in thesidewall of the tire. The contribution to deflection is due mainly tothe bearing structure part situated radially inward. It can be seen, inFIGS. 6 and 7, that the deflection due to loading leads to a decrease ofthe radius of curvature of the support elements: “R” in FIG. 6, showingthe unloaded non pneumatic tire, is greater than “r” in FIG. 7, showingthe loaded non pneumatic tire.

Turning to the mounting of the non-pneumatic tire proposed by theinvention, in the case of a standard tire, it is known that the rim hasroughly the width of the tire. Here, on the other hand, thenon-pneumatic tire projects widely on both sides of the centralmechanical part taking the place of a rim, which has been more generallydescribed in the introduction to the invention by the more functionalexpression “means of connection to a hub.” The means can take highlyvaried forms. It can involve a disk similar to a wheel disk, ending in arevolving part, the meridian profile of which is an open groove towardthe wider radii, made, for example, in two parts in order to be able totighten a rib of the non-pneumatic tire having a complementary shape. Itcan also involve a wheel of the type described in U.S. Pat. No.5,071,196, that is, without any disk. In short, to state the essentials,the means of connection to a hub are rigid, as is the wheel with its rimin the current state of the art.

As for the material constituting the base pieces, it is advantageously acomposite material, that is, a combination of different materials. Thesupport elements illustrated here are laminated elements. The geometryof the support elements makes it possible to offer them the resiliencedesired without attaining the breaking points or elastic limit to thedeformations encountered. Each of the sheets is very narrow in order tooffer a substantial deflection. Each one is able to accommodate smallradius on bending. None is capable of alone bearing the nominal loadsought. By multiplying the sheets, their contribution to support theload are added. The sheets are integrated with one another by the rubberadhering to the sheets. Due to a stacking of some very thin sheets, asufficient bearing is obtained, while being able to attain very highdeflection.

The architecture of the tire proposed makes it possible to manufacturetires designed to operate without inflation pressure (non-pneumatictire). Note, and this is important, nothing prevents imparting a certainair pressure to the proposed tire. It is sufficient, of course, toarrange for the tire to be airtight. An adequate skin is added to thebearing structure, which is useful in any case to prevent fouling of theinner cavity. The characteristics, resilience, notably, can then beadjusted by working with pressurization of the inner cavity. In doing acomparison with a inflated pneumatic tire, the pressurization referredto here is related to the variations around the rated pressure for whichthe pneumatic tire is designed. That is to say that, if according to thefinal destination of a pneumatic tire on different specific cars, thetire is used at pressure ranging from P to P±ΔP, the non pneumatic tirein accordance with this invention can be actually used in the range of 0(no pressure at all) to 0+ΔP. But this is only one means of adjustmentamong others that are more structural, which have been explained, thenon-pneumatic tire of this invention having been actually assigned towork at zero pressure in normal operation.

One advantage of the present invention is to propose an architecturewhich makes it possible, in particular, both to bear the desired loadand to absorb without damage very isolated obstacles like a stone on theroad.

Another advantage of the invention is to ensure, other than bytightening of a bead on a rim, the connection between the tire and therim or the part or parts taking the place of a rim in order to give thereference that is the axis of rotation. This results in a saving ofmaterials and, therefore, a weight advantage of this tire portion.

It has been seen that the resilient non-pneumatic tire includes abearing structure, a tread radially outside the bearing structure andmeans of attachment to a rigid rim or to an equivalent mechanical part.It has also been seen that the bearing structure has a plurality ofsupport elements juxtaposed and distributed all around thecircumference, each support element being placed in a mainly transverseand generally radial orientation, so that each support elementsuccessively enters into play to transfer a fraction of the load of thenon-pneumatic tire from the tread to the hub, when the tire is rollingand is loaded, transfer of the load subjecting each element essentiallyto bending stress. Moreover, it has been observed, with the embodimentsaccording to FIGS. 6 to 11, that upon increase of the transversalstresses as occurring for example in turns, a slight decrease of theradial deflection occurs, providing an anti-roll effect.

In short, the support elements advantageously consist of laminatedelements including a stack of resilient sheets, the resilient sheetsbeing radially superposed and separated by a layer of elastomer adheringto each of the sheets, bending of the laminated elements beingaccompanied by a relative tangential displacement between sheets and bya shear stress of the elastomer, each laminated element being radiallyresilient under the effect of the working stresses, the bending of alaminated element transferring a moment to the means of attachment. Inaddition, it has been seen that the bearing structure includes means ofinterconnection between the support elements (the laminated elements),arranged so that a portion of the radial stress of the support elementsis transferred to the circumferentially adjacent laminated elements,while allowing differences in displacement between adjacent laminatedelements. These means of interconnection can involve the supportelements over their whole length or only over part of same, particularlyunder the tread. The bearing structure is so arranged that, when theradial deflection taken by the non-pneumatic tire brings the radiallyouter part of the bearing structure against the zone of attachment tothe rim (immobile), the resulting stresses due to bending in the supportelements are less than the breaking point (and are less than the elasticlimit if a material having an elastic limit less than the breaking pointis included in the composition of the base pieces).

1. A non-pneumatic tire having a bearing structure, extendingcircumferentially about an axis of rotation and including a radiallyinner wall, a radially outer wall and sidewalls joining the radiallyinner and outer walls so as to define therewithin, at least partially,an inner cavity of revolution, and a tread carried by the radially outerwall of the bearing structure, said bearing structure comprising: a zoneof attachment on the radially inner wall for connecting the bearingstructure to means of connection to a hub, said zone of attachment beinglocated axially between the axial outer limits of the radially innerwall and having an axial extent not greater than 50% of the axialdistance between the axially outer limits of the sidewalls; a pluralityof support elements aligned substantially crosswise to thecircumferential direction and extending in the crosswise directionthroughout the radially inner wall from at least the axial sides of thezone of attachment to the sidewalls, and at least partially through theradially outer wall adjacent to the tread, said support elements beingcircumferentially juxtaposed and distributed around the circumference ofthe bearing structure, each support element including a bundle ofsuperimposed resilient base pieces, separated by a layer of elastomeradhering to each of the base pieces, so as to form a beam capable ofundergoing bending stress and flexing radially at least along a part ofits crosswise length when the tire is loaded, wherein the non-pneumatictire bears a load for its intended use without inflation; and aninterconnecting structure interconnecting portions of the supportelements in at least the radially outer wall and arranged so that aportion of a radial stress of a support element is transferred to thecircumferentially adjacent support elements, while allowing differencesin displacement between adjacent support elements.
 2. A non-pneumatictire according to claim 1, in which said support elements are continuousunder the tread.
 3. A non-pneumatic tire according to claim 1, in whichthe base pieces are made of composite material.
 4. A non-pneumatic tireaccording to claim 1, in which the support elements are, axiallyadjacent the zone of attachment, oriented in a direction roughlyparallel to the axis of rotation.
 5. A non-pneumatic tire according toclaim 1, in which the zone of attachment is roughly centered between theaxial limits of said tire.
 6. A non-pneumatic tire according to claim 1,in which the zone of attachment is in one piece.
 7. A non-pneumatic tireaccording to claim 1, in which the zone of attachment iscircumferentially slotted, so that the tire presents, at the zone ofattachment, a slot between two connecting ribs, wherein the connectingribs are capable of being axially displaced relative to each other.
 8. Anon-pneumatic tire according to claim 1, in which the width of eachsupport element in the circumferential direction is constant.
 9. Anon-pneumatic tire according to claim 1, in which the base pieces areformed from a thermosetting or thermoplastic resin matrix, reinforced byfibers mainly placed longitudinally in each base piece.
 10. Anon-pneumatic tire according to claim 1, in which the circumferentialdimension of each support element is such that the number of supportelements in the whole circumference is at least
 80. 11. A non-pneumatictire according to claim 1, in which the circumferential dimension ofeach support element is such that the number of support elements in thewhole circumference is at least
 200. 12. A non-pneumatic tire accordingto claim 1, in which the interconnecting structure includescircumferential reinforcements at least under the tread.
 13. Anon-pneumatic tire according to claim 1, in which the interconnectingstructure contains a rubber matrix separating the circumferentiallyadjacent support elements.
 14. A non-pneumatic tire according to claim1, in which the support elements are arranged roughly radially.
 15. Anon-pneumatic tire according to claim 1, in which the zone of attachmentincludes at least one circumferentially inextensible reinforcement. 16.A non-pneumatic tire according to claim 1, wherein said supportelements, which are aligned substantially crosswise to thecircumferential direction and extend in the crosswise directionthroughout the radially inner wall from at least the axial sides of thezone of attachment and at least partially through the radially outerwall adjacent to the tread, also extend throughout the sidewalls.
 17. Atire assembly comprising a resilient nonpneumatic tire and a rigid rimon which the tire is mounted, wherein said assembly comprises: (a) arim; (b) a non-pneumatic tire comprising a bearing structure, extendingcircumferentially about an axis of rotation and including a radiallyinner wall, a radially outer wall and sidewalls joining the radiallyinner and outer walls so as to define therewithin, at least partially,an inner cavity of revolution, and a tread carried by the radially outerwall of said bearing structure, said bearing structure furthercomprising: (1) a zone of attachment on the radially inner wall forconnecting the bearing structure to said rim, said zone of attachmentbeing located axially between the axially outer limits of the radiallyinner wall and extending beyond the axial width of said rim; and (2) aplurality of support elements aligned substantially crosswise to thecircumferential direction and extending in the crosswise directionthroughout the radially inner wall from at least the axial sides of thezone of attachment, throughout the sidewalls and at least partiallythrough the radially outer wall adjacent to the tread, said supportelements being circumferentially juxtaposed and distributed around thecircumference of the bearing structure, each support element including abundle of superimposed resilient base pieces, separated by a layer ofelastomer adhering to each of the base pieces, so as to form a beamcapable of undergoing bending stress and flexing radially at least alonga part of its crosswise length when the tire is loaded, wherein thenon-pneumatic tire bears a load for its intended use without inflation;and (c) an interconnecting structure interconnecting portions of supportelements in at least the radially outer wall and arranged so that aportion of a radial stress of a support element is transferred to thecircumferentially adjacent support elements, while allowing differencesin displacement between adjacent support elements.
 18. A non-pneumatictire having a bearing structure, extending circumferentially about anaxis of rotation and including a radially inner wall and a radiallyouter wall defining therebetween, at least partially, an inner cavity ofrevolution, and a tread carried by the radially outer wall of thebearing structure, said bearing structure comprising: a zone ofattachment on the radially inner wall for connecting the bearingstructure to means of connection to a hub, said zone of attachment beinglocated axially between the axial outer limits of the radially innerwall, wherein the zone of attachment is circumferentially slotted, sothat the tire presents two connecting ribs, capable of being axiallydisplaced relative to each other; a plurality of support elementsaligned substantially crosswise to the circumferential direction andextending in the crosswise direction, in the radially inner wall, fromat least the axial sides of the zone of attachment towards the axiallyouter ends of the radially inner wall and, in the radially outer wall,from one axial end thereof to the other, said support elements beingcircumferentially juxtaposed and distributed around the circumference ofthe bearing structure, each support element including a bundle ofsuperimposed resilient base pieces, separated by a layer of elastomeradhering to each of the base pieces, so as to form a beam capable ofundergoing bending stress and flexing radially at least along a part ofits crosswise length when the tire is loaded, wherein the non-pneumatictire bears a load for its intended use without inflation; and aninterconnecting structure interconnecting portions of the supportelements in at least the radially outer wall and arranged so that aportion of a radial stress of a support element is transferred to thecircumferentially adjacent support elements, while allowing differencesin displacement between adjacent support elements.
 19. A non-pneumatictire having a bearing structure, extending circumferentially about anaxis of rotation and including a radially inner wall and a radiallyouter wall defining therebetween, at least partially, an inner cavity ofrevolution, and a tread carried by the radially outer wall of thebearing structure, said bearing structure comprising: a zone ofattachment on the radially inner wall for connecting the bearingstructure to means of connection to a hub, said zone of attachment beinglocated axially between the axial outer limits of the radially innerwall; a plurality of support elements aligned substantially crosswise tothe circumferential direction and extending in the crosswise direction,in the radially inner wall, from at least the axial sides of the zone ofattachment towards the axially outer ends of the radially inner walland, in the radially outer wall, from one axial end thereof to theother, said support elements being circumferentially juxtaposed anddistributed around the circumference of the bearing structure, eachsupport element including a bundle of superimposed resilient basepieces, separated by a layer of elastomer adhering to each of the basepieces, so as to form a beam capable of undergoing bending stress andflexing radially at least along a part of its crosswise length when thetire is loaded, wherein the non-pneumatic tire bears a load for itsintended use without inflation, wherein, at least in support elementssituated under the tread, the length of each of the base pieces in theaxial direction being shorter the further is such base piece locatedfrom the cavity outward; and an interconnecting structureinterconnecting portions of the support elements in at least theradially outer wall and arranged so that a portion of a radial stress ofa support element is transferred to the circumferentially adjacentsupport elements, while allowing differences in displacement betweenadjacent support elements.
 20. A non-pneumatic tire having a bearingstructure, extending circumferentially about an axis of rotation andincluding a radially inner wall and a radially outer wall and sidewallsjoining the radially inner and outer walls so as to define therewith, atleast partially, an inner cavity of revolution, and a tread carried bythe radially outer wall of the bearing structure, said bearing structurecomprising: a zone of attachment on the radially inner wall forconnecting the bearing structure to means of connection to a hub, saidzone of attachment being located axially between the axial outer limitsof the radially inner wall; a plurality of support elements alignedsubstantially crosswise to the circumferential direction and extendingin the crosswise direction throughout the radially inner wall from atleast the axial sides of the zone of attachment, throughout thesidewalls and at least partially through the radially outer walladjacent to the tread, said support elements being circumferentiallyjuxtaposed and distributed around the circumference of the bearingstructure, each support element including a bundle of superimposedresilient base pieces, separated by a layer of elastomer adhering toeach of the base pieces, so as to form a beam capable of undergoingbending stress and flexing radially at least along a part of itscrosswise length when the tire is loaded, wherein the non-pneumatic tirebears a load for its intended use without inflation, the portions of thesupport elements in the radially inner wall which extend axially fromthe zone of attachment towards said sidewalls being at least roughlyparallel to the axis of rotation in absence of load on the tire; and aninterconnecting structure interconnecting portions of support elementsin at least the radially outer wall and arranged so that a portion of aradial stress of a support element is transferred to thecircumferentially adjacent support elements, while allowing differencesin displacement between adjacent support elements.
 21. A non-pneumatictire having a bearing structure, extending circumferentially about anaxis of rotation and including a radially inner wall, a radially outerwall and sidewalls joining the radially inner and outer walls so as todefine therewithin, at least partially, an inner cavity of revolution,and a tread carried by the radially outer wall of the bearing structure,said bearing structure comprising: a zone of attachment on the radiallyinner wall for connecting the bearing structure to means of connectionto a hub, said zone of attachment being located axially between theaxial outer limits of the radially inner wall; and a plurality ofsupport elements aligned substantially crosswise to the circumferentialdirection and extending in the crosswise direction throughout theradially inner wall from at least the axial sides of the zone ofattachment to the sidewalls and at least partially through the radiallyouter wall adjacent to the tread, said support elements beingcircumferentially juxtaposed and distributed around the circumference ofthe bearing structure, each support element including a bundle ofsuperimposed resilient base pieces, separated by a layer of elastomeradhering to each of the base pieces, so as to form a beam capable ofundergoing bending stress and flexing radially at least along a part ofits crosswise length outside of the zone of attachment on the radiallyinner wall when the tire is loaded, wherein the non-pneumatic tire bearsa load for its intended use without inflation; and an interconnectingstructure interconnecting portions of the support elements in at leastthe radially outer wall and arranged so that a portion of a radialstress of a support element is transferred to the circumferentiallyadjacent support elements, while allowing differences in displacementbetween adjacent support elements.